114 ECHINODERMATA. 



for their reception, under tlie name of Ophiura. Possibly this is designed 

 to infer a resemblance between the curving and t^vinmg■ of the rays, or 

 of motions similar to those of the serpent. 



Such a subdivision is not inconvenient ; for although we are not 

 to forget that the Ophiura is still a Star- fish, it is sanctioned by some 

 prominent distinctions from the others. 



The Ophiurce are characterised by a central disc, mth five long 

 slender I'aj^s issuing from the cu'cumference immediatel}', or from the 

 margin of the upper or under surface, in general somewhat within the 

 circumference ; but in several their origin approaches the orifice of the 

 mouth. 



The disc is circular or sub-angular, the mouth generally pentagonal 

 in the under surface, and very dilatable. Five serrated angular prolon- 

 gations of the sui'face below are directed inwards, as if towards the centre, 

 as in the bradeata. Its upper surface is nearly smooth in some, and in 

 others clothed with very minute scales or spines. But its chief variety 

 is in colour, and in the distribution of colours. 



Instead of the wonted suckers specially serving for the motion and 

 adhesion of the Asterias, the rays of the Ophiura consist of segments, 

 and are provided with an infinity of singular spinous processes along 

 each side, together with their accessory parts, which are different in every 

 species of the animal. 



The rays are also covered by scales, in great variety of form, arrange- 

 ment, and distribution, according to the species. 



These organs are extremely liable to mutilation, from their length 

 and slenderness, and because they are so easily entangled with any foreign 

 substance. But the reproductive faculties seem less energetic here than 

 in the animals of the fii'st section. 



Probably the form of the Ophiuree undergoes a considerable modifi- 

 cation Avith age. I have had many small specimens, which I was for 

 some time induced to consider the type of different species ; yet after 

 more mature deliberation, I abandoned my intention of representing 

 them here, as their more prominent distinctive features might be oblite- 

 rated with advances to perfection. 



The vigour and the dimensions of this ci-eature depend much on the 



